The present application is related to a method for detection of a signal, the method comprising the steps of performing continuously a direction finding in time-frequency intervals within a time range and a frequency range, determining for each frequency interval a distribution of the direction finding results, DFRs, for all time intervals and evaluating the determined distribution of direction finding results, DFRs, to detect the existence of a signal emitted by a signal source.

An apparatus for estimating a direction of arrival includes an antenna, a beamforming network, and an evaluator. The antenna is configured to receive signals, is circularly polarized, and includes a plurality of different radiation patterns. The beamforming network is configured to provide based on signals received by the antenna decomposed signals that are received by associated radiation patterns of the plurality of radiation patterns. The evaluator is configured to estimate the direction of arrival based on the decomposed signals and based on information describing signal receiving characteristics of the antenna. The invention also refers to a corresponding method.

Systems and methods are provided in which a direction of arrival of a radio frequency (RF) signal received by a plurality of antennas is determined. A plurality of first converter receives RF signals from the plurality of antennas and outputs a minimum of a first optical signal and a second optical signal each modulated by their corresponding RF signal. A plurality of second converters receives a minimum of the first optical signal via a first optical channel that introduces a first delay and the second optical signal via a second optical channel that introduces a second delay. The second converter outputs a first RF signal that corresponds to the RF modulation on the first optical signal and a second RF signal that corresponds to the RF modulation on the second optical signal. A switch serially receives, from the second converter outputs, the first RF signal and the second RF signal. A direction finding subsystem determines a direction of arrival using a phase difference between the first RF signal and the second RF signal.

Systems and methods are provided in which a direction of arrival of a radio frequency (RF) signal received by a plurality of antennas is determined. A plurality of first converter receives RF signals from the plurality of antennas and outputs a minimum of a first optical signal and a second optical signal each modulated by their corresponding RF signal. A plurality of second converters receives a minimum of the first optical signal via a first optical channel that introduces a first delay and the second optical signal via a second optical channel that introduces a second delay. The second converter outputs a first RF signal that corresponds to the RF modulation on the first optical signal and a second RF signal that corresponds to the RF modulation on the second optical signal. A switch serially receives, from the second converter outputs, the first RF signal and the second RF signal. A direction finding subsystem determines a direction of arrival using a phase difference between the first RF signal and the second RF signal.

A method of determining a direction of arrival of a signal at a device comprising an antenna with multiple antenna elements, in a processor of the device configured to calculate an average signal for each antenna element based on the signal received at the antenna element over N time slots, determine respective phases of the average signals and determine at least one of an azimuth and elevation angle of the signal using the determined phases and information of the location of the antenna elements.

A system and method for determining a direction of arrival of an incoming signal is disclosed. The present system utilizes a plurality of pseudo-spectrums to create a more accurate result matrix. The pseudo-spectrums are one or two dimensional arrays, where peaks in the arrays are indicative of the angle of arrival. A result matrix is generated by performing a mathematical operation of corresponding elements in each pseudo-spectrum. This mathematical operation may be addition or multiplication. The result matrix provides a more accurate indication of the angle of arrival than can otherwise by achieved. In some embodiments, a measure of quality may also be calculated for the result matrix.

A sparse DOA estimation is based on a multi-level prime arrays (MLPAs) as a general structure for coprime arrays. The array uses multiple uniform subarrays or levels where the number of antenna elements of the subarrays are pairwise coprime integers. The subarrays overlap only at their first antenna element by adjusting the inter-element spacing. By selecting the number of antennas of the subarrays and controlling the inter-element spacing, various MLPAs of different features can be constructed. The configuration that realizes the maximum number of unique lags is recommended because the DOF is upper bounded by the number of lags.

A system and method to resolve angle of arrival (AOA) ambiguity in a radar system include receiving received reflections at a plurality of transceiver nodes. Each transceiver node among the plurality of transceiver nodes of the radar system receives one or more of the received reflections at respective one or more receive elements. The method includes determining candidate AOAs {circumflex over ()}.sub.i based on phases differences in the received reflections at the plurality of transceiver nodes, and determining Doppler frequencies f.sub.d.sup.i based on the received reflections. An estimated AOA {circumflex over ()} is selected from among the candidate AOAs {circumflex over ()}.sub.i based on matching metrics .sub.i between the Doppler frequencies and the candidate AOAs {circumflex over ()}.sub.i.

Methods and systems for spatial filtering transmitters and receivers capable of simultaneous communication with one or more receivers and transmitters, respectively, the receivers capable of outputting source directions to humans or devices. The methods and systems use spherical wave field partial wave expansion (PWE) models for transmitted and received fields at antennas and for waves generated by contributing sources. The source PWE models have expansion coefficients expressed as functions of directional coordinates of the sources. For spatial filtering receivers a processor uses the output signals from at least one sensor outputting signals consistent with Nyquist criteria representative of the wave field and the source PWE model to determines directional coordinates of sources (wherein the number of floating point operations are reduced) and outputs the directional coordinates and communications to a reporter configured for reporting information to humans. For spatial filtering transmitters a processor uses known receiver directions and source partial wave expansions to generate signals for transducers producing a composite total wave field conveying communications to the specified receivers. The methods and communications reduce the processing required for transmitting and receiving spatially filtered communcations.

Methods and systems for spatial filtering transmitters and receivers capable of simultaneous communication with one or more receivers and transmitters, respectively, the receivers capable of outputting source directions to humans or devices. The methods and systems use spherical wave field partial wave expansion (PWE) models for transmitted and received fields at antennas and for waves generated by contributing sources. The source PWE models have expansion coefficients expressed as functions of directional coordinates of the sources. For spatial filtering receivers a processor uses the output signals from at least one sensor outputting signals consistent with Nyquist criteria representative of the wave field and the source PWE model to determines directional coordinates of sources (wherein the number of floating point operations are reduced) and outputs the directional coordinates and communications to a reporter configured for reporting information to humans. For spatial filtering transmitters a processor uses known receiver directions and source partial wave expansions to generate signals for transducers producing a composite total wave field conveying communications to the specified receivers. The methods and communications reduce the processing required for transmitting and receiving spatially filtered communcations.